Separation of oxygen containing gases

ABSTRACT

The present invention is directed to a method and a system for separating oxygen from air. A compressible air stream that contains oxygen is mixed in a substantially co-current flow with an incompressible fluid stream comprising an incompressible fluid in which oxygen is capable of being preferentially absorbed. Rotational velocity is imparted to the mixed streams, separating an incompressible fluid in which at least a portion of the oxygen is absorbed from other compressible components of the air stream. The compressible air stream may be provided at a stream velocity having a Mach number of at least 0.1.

FIELD OF THE INVENTION

The invention relates to the separation of one or more components from agas stream containing a plurality of gaseous components. Moreparticularly, the invention relates to a system and method for removingone or more compressible components from a compressible stream using aseparation device and an incompressible fluid.

BACKGROUND OF THE INVENTION

Numerous methods and apparatus exist for separating components from afluid stream containing gases, liquids and/or solids. Conventionalseparation apparatuses include distillation columns, stripping columns,filters and membranes, centrifuges, electrostatic precipitators, dryers,chillers, cyclones, vortex tube separators, and absorbers. These methodsand devices are relatively ineffective and/or inefficient in separatinggas components of gaseous mixtures.

For example, a commonly utilized system and method for separation ofhydrogen sulfide (H2S) or carbon dioxide (CO2) from a gas streaminvolves using a series of stripping columns to absorb target gaseouscomponents into a solvent/reactant followed by the distillation of thesolvent/reactant to recover the target gas components. The equipmentinvolved usually requires a large footprint due to the numerous piecesof process equipment needed for such a separation scheme. Such a processmay also suffer from high energy consumption requirements andsolvent/reactant loss during operation.

A conventional amine plant exemplifies the requirements of anabsorption/distillation sequence used to remove a target component froma gas stream. In general, this process involves contacting a gas streamcomprising a target component with a reactant in a stripping column. Thegas removed from the stripping column is clean gas with the majority ofthe target component removed. The reactant is conventionally an aminethat forms a complex with a target component such as carbon dioxide. Thetarget-component enriched complex then passes to a regenerator tower,which may be a stripping column or distillation tower, where the complexis heated to release the target component. Additional equipment requiredto operate the amine unit typically includes flash tanks, pumps,reboilers, condensers, and heat exchangers. When the gas stream containstoo high of a target component concentration, the energy required toremove the target component may exceed the useful chemical energy of thestream. This limitation sets an upper concentration level of the targetcomponent at which the process can be economically operated. Thisprocess also suffers from a high energy consumption, solvent loss, and alarge footprint, making the process impracticable for offshore use.

Separation of gaseous components of a gas mixture such as air has alsobeen effected by contacting the gas mixture with selectively permeablefilters and membranes. Filtration and membrane separation of gasesinclude the selective diffusion of one gas through a membrane or afilter to effect a separation. The component that has diffused throughthe membrane is usually at a significantly reduced pressure relative tothe non-diffused gas and may lose up to two thirds of the initialpressure during the diffusion process. Thus, filters and membraneseparations require a high energy consumption due to the energy requiredto re-compress the gas diffused through the membrane and, if the feedstream is at low pressure, the energy required to compress the feedstream to a pressure sufficient to diffuse one or more feed streamcomponents through the membrane. In addition, membrane life cycles canvary due to plugging and breakdown of the membrane, requiring additionaldowntime for replacement and repair.

Centrifugal force has been utilized to separate gaseous components fromgas-liquid feed streams. For example, cyclones utilize centrifugal forceto separate gaseous components from gas-liquid fluid flows by way ofturbulent vortex flow. Vortices are created in a fluid flow so thatheavier particles and/or liquid droplets move radially outward in thevortex, thus becoming separated from gaseous components. Within acyclone, the gas and liquid feed stream flow in a counter-current flowduring separation such that the heavier components and/or liquiddroplets are separated from the gaseous components by gravity in adownward direction after the initial separation induced by the vortexwhile the gaseous components are separated in the opposite direction.Considerable external energy must be added to cyclones to achieveeffective separation.

U.S. Pat. No. 6,524,368 (Betting et al.) refers to a supersonicseparator for inducing condensation of one or more components followedby separation. Betting is directed to the separation of anincompressible fluid, such as water, from a mixture containing theincompressible fluid and a compressible fluid (gas). In this process, agas stream containing an incompressible fluid and a compressible fluidis provided to a separator. In the separator, the gas stream convergesthrough a throat and expands into a channel, increasing the velocity ofthe gas stream to supersonic velocities, inducing the formation ofdroplets of the incompressible fluid separate from the gas stream (andthe compressible fluid therein). The incompressible fluid droplets areseparated from the compressible fluid by subjecting the droplets and thecompressible fluid to a large swirl thereby separating the fluiddroplets from the compressible fluid by centrifugal force. The systeminvolves a significant pressure drop between the inlet and outletstreams, and a shock wave occurs downstream after the separation, whichmay require specialized equipment to control.

It has been proposed to utilize centrifugal force to separate gascomponents from a gaseous mixture. In a thesis by van Wissen (R.J.E. VANWISSEN, CENTRIFUGAL SEPARATION FOR CLEANING WELL GAS STREAMS: FROMCONCEPT TO PROTOTYPE (2006)), gas centrifugation is described forseparating two compressible fluids in the absence of an incompressiblefluid. The separation is carried out using a rotating cylinder to createa plurality of compressible streams based on the difference in themolecular weight of the gaseous components. As noted in the thesis, thepotential to separate compressible components such as carbon dioxidefrom light hydrocarbons is limited by the differences in molecularweights between the components. As such, centrifuges cannot provide ahighly efficient separation when the component molecular weights areclose to one another. Such a design also suffers from an extremely lowseparation throughput rate that would require millions of centrifuges tohandle the output of a large gas source.

What is needed is a separation apparatus and method that provides highseparation efficiency of compressible components while avoiding orreducing pressure drop, and the need to supply large amounts of externalenergy.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a method comprisingproviding a compressible feed stream comprising a first compressiblecomponent and a second compressible component, where the firstcompressible component is oxygen; providing an incompressible fluidstream comprised of an incompressible fluid capable of absorbing oxygenor reacting with oxygen; mixing the compressible feed stream and theincompressible fluid stream to form a mixed stream, where thecompressible feed stream is provided for mixing at a first linearvelocity in a first direction and the incompressible fluid stream isprovided for mixing at a second linear velocity in a second direction,the second linear velocity having a velocity component in the samedirection as the first direction, where the mixed stream has aninstantaneous third linear velocity in a third direction and iscomprised of the second compressible component and a constituentselected from the group consisting of a mixture of the oxygen and theincompressible fluid, a chemical compound or adduct of a reactionbetween the oxygen and the incompressible fluid, and mixtures thereof;imparting a rotational velocity to the mixed stream, where the directionof the rotational velocity is tangential or skew to the third directionof the instantaneous third linear velocity of the mixed stream; andseparating an incompressible fluid product stream from the mixed stream,where the incompressible fluid product stream contains at least aportion of the constituent of the mixed stream, and where theincompressible fluid product stream is separated from the mixed streamas a result of the rotational velocity imparted to the mixed stream.

In another aspect, the present invention is directed to a methodcomprising providing a compressible feed stream comprising a firstcompressible component and a second compressible component, wherein thefirst compressible component is oxygen; and separating the compressiblefeed stream into a first compressible product stream comprising at least60% of the second compressible component and a second compressibleproduct stream comprising at least 60% of the first compressiblecomponent, wherein the compressible feed stream has a velocity with aMach number of greater than 0.1, or at least 0.2, or at least 0.3, or atleast 0.4.

In a further aspect, the present invention is directed to a systemcomprising: a compressible fluid separation device that receives anincompressible fluid stream comprising an incompressible fluid and acompressible feed stream comprising oxygen and a second compressiblecomponent and separates the compressible feed stream into a firstcompressible product stream comprising at least 60% of the secondcompressible component and an incompressible fluid product streamcomprising at least 60% of the oxygen; an incompressible fluidregenerator that receives the incompressible fluid product stream anddischarges an oxygen depleted incompressible fluid and a secondcompressible product stream enriched in the oxygen; and anincompressible fluid injection device that receives the oxygen depletedincompressible fluid and mixes the oxygen depleted incompressible fluidwith the compressible feed stream.

The features and advantages of the present invention will be apparent tothose skilled in the art. While numerous changes may be made by thoseskilled in the art, such changes are within the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments ofthe present invention, and should not be used to limit or define theinvention.

FIG. 1 schematically illustrates an embodiment of a separation processof the invention.

FIG. 2 schematically illustrates another embodiment a separation processof the invention.

FIG. 3 schematically illustrates an embodiment of a separation processof the invention.

FIG. 4 schematically illustrates still another embodiment of aseparation process of the invention.

FIG. 5 schematically illustrates yet another embodiment of a separationprocess of the invention.

FIG. 6 schematically illustrates an embodiment of an incompressiblefluid separation device.

DETAILED DESCRIPTION OF THE INVENTION

The system and method of the present invention utilizes centrifugalforce to remove oxygen from a feed gas stream while limiting pressuredrop and energy consumption. Oxygen can be removed from a feed gasstream with lower energy consumption than a conventional process, suchas a cryogenic or membrane processes. For example, an air stream may beprocessed using the system and method of the present invention toproduce a purified nitrogen or oxygen stream ready for use in anindustrial process. The pressure drop between the feed and productstreams may also be limited, avoiding or at least limitingre-compression needs downstream of the process relative to conventionalgas separation processes. The process also utilizes relatively fewpieces of equipment, thus limiting the overall footprint of the process.The system and methods of the present invention utilize anincompressible fluid to aid in the removal of a target component fromthe gas stream. Certain advantages of specific embodiments will bedescribed in more detail below.

Referring to FIG. 1, an embodiment of a system 100 is shown having acompressible feed stream 102, an incompressible fluid stream 108, aseparation device 104, a first compressible product stream 106, aplurality of incompressible product streams 112, 116, 118, and anincompressible fluid regenerator 110 that produces one or more secondcompressible product streams 114, 120, 122. The process functions toseparate oxygen as a compressible target component from the compressiblefeed stream 102 and produces a first compressible product stream 106 andone or more second compressible product stream(s) 114, 120, 122, whereone of the second compressible product streams is rich in oxygen. Thenumber of compressible product streams will depend on the number oftarget components or target component groups in addition to oxygen thatare removed from the compressible feed stream 102. As used herein, theterm “target component” refers to oxygen and one or more othercompressible components that are separated from the compressible feedstream individually or as a group, and the use of the term in thesingular can include a plurality of compressible components. Thecompressible feed stream 102 comprises a plurality of compressiblecomponents, at least one of which is oxygen that is to be separated fromother compressible components in the feed stream 102.

An incompressible fluid stream 108 comprised of an incompressible fluidis provided that is mixed with the compressible feed stream 102 in asubstantially co-current flow to create a mixed stream comprising amixture of compressible components and incompressible fluid prior to,upon entering, and/or within the separation device 104. In anembodiment, optional incompressible fluid streams 124 & 126 may beprovided and mixed in a substantially co-current flow with thecompressible components within the separation device to further enhancethe separation of the compressible components.

As used herein, a mixing an incompressible fluid stream and acompressible feed stream in a “substantially co-current flow” refers toa process in which the compressible feed stream is provided for mixingat a first linear velocity in a first direction, the incompressiblefluid stream is provided for mixing at a second linear velocity in asecond direction, where the second linear velocity has a velocitycomponent in the same direction as the first direction of the firstlinear velocity of the compressible feed stream (e.g. the second linearvelocity of the incompressible fluid stream has a vector directed alongan axis defined by the first direction of the first linear velocity ofthe compressible feed stream in the direction of the first direction),and the compressible feed stream having the first linear velocity in thefirst direction is mixed with the incompressible fluid stream having thesecond linear velocity in the second direction to form the mixed streamhaving a third linear velocity in a third direction. As used herein, the“linear velocity” refers to a velocity vector with a direction for aspecified component or stream at a specific time or at a specific pointwithin the separation device which does not necessarily have a constantdirection with respect to one or more axes of the separation device. Thelinear velocity of the mixed stream may change direction with time,therefore the third direction is defined herein as the direction of theinstantaneous linear velocity of the mixed stream (i.e. theinstantaneous third linear velocity). The third linear velocity of themixed stream may have a velocity component in the same direction as thefirst direction of the first linear velocity of the compressible feedstream and/or may have a velocity component in the same direction as thesecond direction of the second linear velocity of the incompressiblefluid stream (i.e the mixed stream has a flow that is substantiallyco-current with the flow of the compressible feed stream and/or theincompressible fluid stream). In an embodiment of the invention, thefirst direction of the first linear velocity of the compressible feedstream, the second direction of the second linear velocity of theincompressible fluid stream, and the third direction of the third linearvelocity of the mixed stream are the same (e.g. the compressible feedstream, the incompressible fluid stream, and the mixed stream have aco-current flow). The magnitude of the first linear velocity of thecompressible feed stream, the second linear velocity of theincompressible fluid stream, and the third linear velocity of the mixedstream, may vary relative to each other.

In the separation device 104, oxygen and any other target components areabsorbed by or reacted with the incompressible fluid of theincompressible fluid stream 108 and is separated from the other“non-target” compressible components of the mixed stream. As usedherein, the term “a mixture of a compressible component and anincompressible fluid” includes a composition in which the compressiblecomponent (i.e. the target component) is absorbed in an incompressiblefluid. In an embodiment, the separation device 104 is a centrifugalforce separator in which a rotational velocity is imparted to the mixedstream, and the incompressible fluid containing the oxygen is separatedfrom the other compressible components of the mixed stream due to therotational motion of the mixed stream flowing through the separator. Therotational motion within a centrifugal force separator can also create astratification within the compressible components of the mixed stream.The heavier compressible and incompressible components of the mixedstream are separated towards the wall of the separation device. Thisstratification can further increase any heavy target component loadingwithin the incompressible fluid.

As used herein, the term “rotational velocity” refers to the velocity ofa stream, flow, or component about an axis in a rotational motion, wherethe axis may be defined by the direction of the instantaneous linearvelocity of the stream, flow, or component. The rotational velocity maybe tangential or skew to the axis defined by the direction of theinstantaneous linear velocity of the stream. For example, the rotationalvelocity imparted to the mixed stream may be tangential or skew to thethird direction (e.g. the direction of the instantaneous third linearvelocity, which is the instantaneous linear velocity of the mixedstream) or may be tangential or skew to the first direction (e.g. thedirection of the first linear velocity, which is the linear velocity ofthe compressible feed stream). Also, as used herein, the “resultantvelocity” refers to the total velocity of a specified component, flow,or stream including its linear velocity and rotational velocitycomponents.

In an embodiment, the first compressible product stream 106 leaves theseparation device and can be used for various downstream purposes. Theincompressible fluid product stream 112 and optional incompressiblefluid product streams 116, 118 leave the separation device 104 and maypass to a second separation process 110 where at least some of thetarget component (e.g., O₂) may be removed from the incompressible fluidproduct stream(s). Oxygen and any other target components may pass outof the second separation process 110 as one or more second compressibleproduct streams 114, 120, 122. Regenerated incompressible fluid mayleave the second separation process 110 to be used as, inter alia, theincompressible fluid stream 108 that is combined and mixed with thecompressible feed stream 102.

Compressible Stream Description

In an embodiment of the invention, the compressible feed streamgenerally includes any multi-component compressible gas containingoxygen that it is desirable to separate into two or more compressibleproduct streams. Exemplary processes include, but are not limited to,the separation of air into its constituent components or the separationof an industrial gas stream containing oxygen and nitrogen into anoxygen enriched stream and a nitrogen enriched stream. When separatingair into its constituent components, the compressible feed stream isair. Purified streams of oxygen, nitrogen, and/or argon may be producedby separating air into its constituent components. Air comprisesapproximately 78 vol % nitrogen, 21 vol % oxygen and less than 1 vol %argon and other gases. Air can also comprise a small percentage of watervapor.

The compressible feed stream may generally be at a pressure ranging from2 bar (0.2 MPa) to 200 bar (20 MPa), and in some instances may be inputinto the process as high as 1000 bar. The temperature of thecompressible feed stream may vary with the source of the gas. In anembodiment, the compressible feed stream may be pre-conditioned, forexample by passing the compressible feed stream through a heatexchanger, such that the compressible feed stream temperature isconditioned to be at or near the freezing point of the incompressiblefluid used in the process. For example, the compressible feed stream maybe conditioned so that the compressible feed stream temperature iswithin 50° C. of the freezing point of the incompressible fluid selectedfor the process.

Outlet Stream Descriptions

The separation process and system described herein can generate a numberof product streams. The first compressible component—the targetcomponent oxygen—of the compressible feed stream can be absorbed orreacted, preferably reversibly, with the incompressible fluid of theincompressible fluid stream upon mixing the compressible feed stream andthe incompressible fluid stream. An incompressible fluid product streamcontaining the incompressible fluid and at least a portion of the firstcompressible component oxygen and/or a chemical compound or adduct of areaction between the incompressible fluid and the first compressiblecomponent oxygen is formed upon separation of the incompressible fluidfrom the mixed stream. The second compressible component of thecompressible feed stream (e.g. nitrogen) can pass through the separationprocess to form a first compressible product stream.

Additional components may pass through the separation device with thesecond compressible component and be contained within the firstcompressible product stream. For example, when an air stream containingoxygen, nitrogen, and argon is input into the process, the compressibleproduct streams may include a first compressible product streamcomprising at least a portion of the nitrogen and a portion of the argonand an incompressible fluid product stream comprising a portion of theoxygen.

In an embodiment of the process and/or system of the present invention,multiple incompressible fluid streams may be mixed in a substantiallyco-current flow with the compressible feed stream and then separatedfrom the mixed stream to generate multiple incompressible fluid productstreams. Such an embodiment may be useful when the compressible feedstream comprises a plurality of target components for removal. Eachincompressible fluid of the individual incompressible fluid streams maybe selected to selectively absorb or react (preferably reversibly) witha selected target component in the compressible feed stream. Themultiple incompressible fluid streams may be mixed with the compressiblefeed stream and separated from the mixed stream in a single separatordevice or in multiple separator devices. In a single separator device,in general, the heaviest compressible components, including thoseabsorbed or reacted with the incompressible fluids, will be removedfirst after imparting rotational velocity to the mixed stream. Whenmultiple separation devices are used, the separation devices may be usedin series to remove one or more components in each separation deviceoptionally using a plurality of incompressible fluids.

The incompressible fluid product stream can be treated to desorb orreversibly release the portion of the first compressible component(e.g., the target component oxygen) to form a second compressibleproduct stream. In an embodiment in which a plurality of incompressiblefluid product streams are formed, a plurality of compressible productstreams can be formed by treating the incompressible fluid productstreams to desorb or reversibly release the portion of the compressiblefeed stream captured by the incompressible fluid product streams.

Additional components beyond oxygen and any other compressible targetcomponents may also be removed from the compressible feed stream. Forexample, the compressible feed stream may comprise an incompressiblesolid component. Solid components that can be found in a feed streaminclude, but are not limited to, solids found in air (e.g., dust) thatare not separated from the compressible components of the compressiblefeed stream. Additional non-solid incompressible components that may befound within the compressible feed stream include water and variousother trace components in air or an industrial stream comprisingnitrogen and oxygen. These components can be removed separately fromother target components of the compressible feed stream by controllingthe operating conditions of the process and system.

In an embodiment of the invention, a centrifugal separator device usedto effect the process is structured to enable the removal of oxygen,optionally one or more additional compressible target components, andone or more additional incompressible components such as solidcomponents, condensable components, and/or water along the length of aseparation section of the separator device. The separator may include aplurality of outlet ports. Use of a plurality of outlet ports allows thevarious components within the compressible feed stream to be removedfrom the separation device in a plurality of product streams with eachproduct stream enriched in a certain type of additional component orincompressible fluid containing one or more compressible targetcomponents. Each compressible target component may then be removed froma system including the separator device as a separate compressibleproduct stream or compressible products stream upon regeneration of anincompressible fluid stream from an incompressible fluid product streamseparated from the mixed stream. The first compressible product streamcomprises the remainder of the compressible components from thecompressible feed stream not separated and removed from the mixed streamas a target component by an incompressible fluid or separated as a solidor liquid from the mixed stream in the system.

In an embodiment, the first and second compressible product streams havedifferent concentrations of at least two components relative to thecompressible feed stream. The separation process is capable ofseparating a compressible target component from the compressible feedstream resulting in a first compressible product stream from which atleast a portion of the target component has been separated and at leastone second compressible product stream enriched in the target component.For example, the invention provides a method comprising: providing acompressible feed stream first compressible component comprised ofoxygen and a second compressible component; providing an incompressiblefluid stream comprised of an incompressible fluid capable of absorbingthe oxygen or reacting, preferably reversibly, with the oxygen; mixingthe compressible feed stream and the incompressible fluid stream to forma mixed stream, where the compressible feed stream is provided formixing at a first linear velocity in a first direction and theincompressible fluid stream is provided for mixing at a second linearvelocity in a second direction, the second linear velocity having avelocity component in the same direction as the first direction, wherethe mixed stream has an instantaneous third linear velocity in a thirddirection and is comprised of the second compressible component and aconstituent selected from the group consisting of a mixture of theoxygen and the incompressible fluid, a chemical compound or adduct of areaction between the oxygen and the incompressible fluid, and mixturesthereof; imparting a rotational velocity to mixed stream, where therotational velocity is directed tangential or skew to the thirddirection of the instantaneous third linear velocity of the mixedstream; and separating an incompressible fluid product stream from themixed stream, where the incompressible fluid product stream comprises atleast a portion of the constituent of the mixed stream, and where theincompressible fluid is separated from the mixed stream as a result ofthe rotational velocity imparted to the mixed stream.

Incompressible Fluids

In an embodiment, a variety of incompressible fluids may be used toremove oxygen and one or more other target components from thecompressible feed stream. At least one of the incompressible fluidsutilized in the process must be capable of absorbing oxygen or reactingwith oxygen at least partially selectively relative to at least oneother compressible component in the compressible feed stream. Anyincompressible fluid capable of absorbing oxygen or reacting, preferablyreversibly reacting, with the oxygen upon contact may be used to removeoxygen from the compressible feed stream. The choice of incompressiblefluid may depend on the properties of the compressible feed stream, theproperties of the incompressible fluid, and the conditions of theprocess or within the separation device. In an embodiment, thesolubilities of oxygen and other components of the compressible feedstream in the incompressible fluid, and their relative solubilities inthe incompressible fluid may determine, at least in part, the choice ofincompressible fluid. The selection of the incompressible fluid may bedetermined, at least in part, by a consideration of the driving forcesfor the solubility of oxygen and non-target component(s) in theincompressible fluid. The driving forces can include, but are notlimited to, polar bonding forces, London dispersion forces, Van derWaalsforces, induced dipole forces, hydrogen bonding, and any otherintermolecular forces that affect solubility of one component inanother.

In an embodiment, the incompressible fluid is a physical solvent.Physical solvents include any solvents capable of absorbing oxygenwithout forming a new chemical compound or adduct. In general, gassolubilities in liquids increase as the temperature of the liquid isdecreased. Further, gas solubilities are related to partial pressureswithin the gas phase such that higher partial pressures tend to resultin greater loading within a liquid in contact with the gas. However,exceptions to these general principles do exist. These generalprinciples indicate that when a physical solvent is used to removeoxygen from the compressible feed stream, the solvent should be cooledor sub-cooled to a temperature near the freezing point of the solvent ifpossible. In an embodiment, a mixture of physical solvents, including amixture of physical solvents and water, is used within the process asthe incompressible fluid to separate oxygen and optionally one or moreadditional compressible target components from the compressible feedstream.

In an embodiment, a fluorinated compound may be used as a physicalsolvent to remove a compressible component comprising oxygen from thecompressible feed stream. The fluorinated compound may comprise aperfluorochemical, which are generally non-polar highly fluorinatedcompounds that can exhibit high solubilities for oxygen. In otherembodiments, the fluorinated compound can comprise a fluorinatedaromatic compound or a fluorinated aliphatic compound, which can includea fluorinated cyclic compound. Suitable fluorinated compounds caninclude, but are not limited to, hexafluorobenzene,perfluorocyclohexane, perfluorocyclohexene, perfluorotributylamine,perfluoro-N-methylpiperidine, N-methylmorpholine, 1,4-difluorobenzene,1,3,5-trifluorobenzene, pentafluorochlorobenzene,perfluoromethylbenzene, perfluoro-n-hexane, perfluoro-n-heptane,perfluoro-n-nonane, and perfluorodecalin. Suitable fluorinated compoundscan include those commercially available as Fluorinert™ Liquidsavailable from 3M Electronic Materials of St. Paul, Minn. Thefluorinated compound generally has a boiling point ranging from 5° C. to45° C., and can be used in a separation process below this temperature.Some solubilities of several compressible components in selectfluorinated compounds are shown in Table 1.

TABLE 1 Solute Solubility Solute Solubility (mole fraction × 10⁴)Solvent O₂ N₂ CO₂ Ar H₂ n-C₇F₁₆ 55.2 38.8 208 53.2 14.0 n-C₈F₁₈ 53.4

35.2 C₆F₆ 24.2 17.9 220 23.9 c-C₆F₁₁CF₃ 45.5 32.7 44.7 (C₄F₉)N 59.6 34.9199 61.0

46.2 31.7 179.7

29.6 1,4-C₆H₄F₂ 9.8 1,3,5-C₆H₃F₃ 11.3 C₆F₅Cl 19.4 C₆F₅CF₃ 23.8C₈F₁₇CH═CH₂ 44.5 C₆F₁₃CH₂CH₂C₆F₁₃ 46.8 C₈F₁₇C₂H₅ 47.1 C₈F₁₇C₈H₁₇ 52.2n-C₆F₁₄ 57.6 (n-C₄F₉)₃N 59.6 C₆F₁₃CH═CHC₆F₁₃ 61.4 c-C₆F₁₀ 29.2

32.5

29.6

As shown in Table 1, some fluorinated compounds demonstrate an increasedsolubility for oxygen, relative to nitrogen, carbon dioxide, and argonand may, therefore, be used to selectively remove oxygen from a mixedstream containing oxygen and nitrogen, carbon dioxide, and/or argon.

Other suitable physical solvents that may be utilized as theincompressible fluid for separating oxygen from nitrogen includemethanol, N-methyl-2-pyrrolidone (NMP), and propylene carbonate (PC).Table 2 lists the freezing point of a solution of methanol and water atvarying concentrations. In an embodiment of the present invention, themethanol or methanol/water mixture may be cooled to near its freezingpoint. For example, methanol or a methanol/water mixture may be used ata temperature of between −40° F. and −145° F. (−40° C. and −98° C.)

TABLE 2 Methanol/Water % wt. Freezing Point, ° F. Freezing Point, ° C. 0/100 32 0 10/90 20 −7 20/80 0 −18 30/70 −15 −26 40/60 −40 −40 50/50−65 −54 60/40 −95 −71 70/30 −215 −137 80/20 −220 −143 90/10 −230 −146100/0  −145 −98NMP can be used for operations at temperatures ranging from ambient to5° F. (−15° C.). PC can be used for operations at temperatures rangingfrom 0° F. (−18° C.) to 149° F. (65° C.). Specific solvent propertiesare listed in Table 3, and relative solubility of oxygen in thesesolvents relative to other elements or compounds is listed in Table 4.

TABLE 3 Physical Properties Property PC NMP Methanol Viscosity at 25° C.3.0 1.65 0.6 (cP) Specific Gravity at 1195 1027 785 25° C. (kg/m³)Molecular Weight 102 99 32 Vapor Pressure at 0.085 0.40 125 25° C.(mmHg) Freezing Point (° C.) −48 −24 −98 Boiling Point at 240 202 65 760mmHg (° C.) Thermal 0.12 0.095 0.122 Conductivity (Btu/hr-ft-° F.)Maximum Operating 65 — — Temperature (° C.) Specific Heat 25° C. 0.3390.40 0.566 CO2 Solubility 0.455 0.477 0.425 (ft³/gal) at 25° C.

TABLE 4 Relative Solubility PC NMP Methanol at at at Gas Component 25°C. 25° C. −25° C. Hydrogen 0.0078 0.0064 0.0054 Nitrogen 0.0084 — 0.012Oxygen 0.026 0.035 0.020 Carbon Monoxide 0.021 0.021 0.020 Methane 0.0380.072 0.051 Ethane 0.17 0.38 0.42 Ethylene 0.35 0.55 0.46 Carbon Dioxide1.0 1.0 1.0 Propane 0.51 1.07 2.35 i-Butane 1.13 2.21 — n-Butane 1.753.48 — Carbonyl Sulfide 1.88 2.72 3.92 Acetylene 2.87 7.37 3.33 Ammonia— — 23.2 Hydrogen Sulfide 3.29 10.2 7.06 Nitrogen Dioxide 17.1 — —Methyl Mercaptan 27.2 — — Carbon Disulfide 30.9 — — Ethyl Mercaptan —78.8 — Sulfur Dioxide 68.6 — — Dimethyl Sulfide — 91.9 — Thiopene — — —Hydrogen Cyanide — — —

As shown in Table 4, oxygen is significantly more soluble in PC and NMPthan nitrogen, although these solvents are generally not effective toseparate oxygen from sulfur or hydrocarbon containing compounds.

In an embodiment, the incompressible fluid is a chemical solvent. Asused herein, a chemical solvent is any solvent that reacts with oxygenand one or more other target components to form a different chemicalcompound or adduct. Preferably the reaction is reversible so thechemical solvent may then be regenerated from the distinct chemicalcompound or adduct by further processing. For example, direct orindirect heating using steam may be used to break a different chemicalcompound or adduct into a regenerated chemical solvent molecule andoxygen in some circumstances.

An incompressible fluid stream comprising a physical solvent and/or achemical solvent may be mixed with the compressible feed stream using amisting nozzle to generate micro scale droplets, as discussed in moredetail below. The incompressible fluid stream pressure will generally bedetermined by the amount of pressure required to inject theincompressible fluid into the compressible feed stream. Theincompressible fluid stream pressure may be between 1 bar (0.1 MPa) and200 bar (20 MPa), or alternatively between 50 (5 MPa) and 100 bar (10MPa).

Separation Device Description

A separation device can be used to separate oxygen and, optionally, oneor more additional target components from a compressible feed streamusing an incompressible fluid. Suitable separation devices include anydevice capable of separating an incompressible fluid product stream froma mixed stream of an incompressible fluid stream and a compressible feedstream by 1) imparting a rotational velocity to the mixed stream and/or2) by forming a mixed stream having a rotational velocity component uponmixing the incompressible fluid stream and the compressible feed stream.Preferably the separation device is structured to form the mixed streamand/or impart rotational velocity to a mixed stream. The mixed streammay be comprised of the incompressible fluid; a constituent selectedfrom the group consisting of a mixture of oxygen and an incompressiblefluid, a chemical compound or adduct of a reaction between oxygen andthe incompressible fluid, and mixtures thereof; and a secondcompressible component from the compressible feed stream (e.g.nitrogen). Imparting rotational velocity to the mixed stream or forminga mixed stream having rotational velocity provides rotational velocityto, at least, the constituent of the mixed stream, and generallyprovides rotational velocity to all the elements of the mixed stream.The linear velocity of the second compressible component of thecompressible feed stream or the mixed stream may be increased at somepoint in the separation device.

In the mixed stream having a rotational velocity component thedifference in momentum between the compressible components not absorbedin the incompressible fluid (i.e. the second compressible component(s))and the incompressible fluid incorporating the oxygen of thecompressible feed stream therein (i.e. the constituent of the mixedstream) can be used to effect a separation of the compressiblecomponents and the incompressible fluid incorporating the oxygentherein. For example, a rotational velocity may be imparted to the mixedstream to cause a continuous change in the direction of flow of themixed stream, thus inducing a centrifugal force on the mixed stream. Inthis example, the incompressible fluid moves outward in response to thecentrifugal force where it may impinge on a surface and coalesce forcollection. In each case, the separator results in the separation of anincompressible fluid from the mixed stream which may be used to separateoxygen and, optionally one or more additional target components from thecompressible feed stream provided the oxygen and any additional targetcomponent(s) are absorbed by or reacted with the incompressible fluid.

In an embodiment, a compressible feed stream containing oxygen is mixedwith an incompressible fluid in a separation device to absorb at least aportion of the oxygen in the incompressible fluid. As used herein,oxygen or any other additional target component may be “absorbed” in theincompressible fluid by physical absorption or by chemically reactingwith the incompressible fluid to form a chemical compound or adduct withthe incompressible fluid. The chemical reaction may be a reversiblechemical reaction.

The compressible feed stream and the incompressible fluid are mixed toallow for absorption of oxygen from the compressible feed stream intothe incompressible fluid thereby producing a mixed stream containing oneor more compressible components and an incompressible fluid in whichoxygen is absorbed. The mixed stream is passed through the separationdevice to produce an incompressible fluid product stream containingoxygen and a compressible product stream comprising the compressiblecomponents from the compressible feed stream that are not absorbed intothe incompressible fluid, for example, nitrogen. The separating deviceuses centrifugal force to separate the incompressible fluid productstream from the compressible product stream. The centrifugal force canalso cause the compressible components of the compressible feed streamto stratify within the separator, increasing the concentration of thehigher molecular weight components near the outer layers of thecirculating gas stream. As used herein, higher molecular weightcompressible components comprise those components of a gas stream withgreater molecular weights than other components in the stream. Forexample, oxygen would be a higher molecular weight component relative tonitrogen in a compressible feed stream comprising air. In an embodimentin which target component(s) comprise one or more higher molecularweight components, the stratification may result in an increasedseparation efficiency of the target component(s).

Suitable separation devices for use with the present invention includeany substantially co-current centrifugal force separation device capableof separating a liquid from a gas, and optionally causing gasstratification within a separation section of the device. The materialsof construction of the separation device may be chosen based on thecompressible feed stream composition, the incompressible fluidcomposition, and the operating parameters of the system. In anembodiment, the separation device may be constructed of stainless steel316 to protect from corrosion.

In an embodiment, one suitable separation device includes an AZGAZin-line gas/liquid separator (available from Merpro of Angus, Scotland).The AZGAZ device utilizes both an internal settling structure along witha swirl inducing structure to remove incompressible liquid droplets froma compressible gas stream. Having generally described the separationdevice, a more detailed description will now be provided.

In an embodiment of the present invention, a compressible feed stream iscombined with an incompressible fluid to form a mixed stream using anymeans known for injecting an incompressible fluid into a compressiblestream. For example, an atomizing nozzle may be used to inject a streamof finely divided incompressible droplets into the compressible feedstream. In another embodiment, a plurality of nozzles may be used todistribute an incompressible fluid within the compressible feed stream.The design of such a system may depend on the flowrates of theincompressible fluid relative to the flowrate of the compressible feedstream, the geometry of the system, and the physical properties of theincompressible fluid.

In an embodiment, an atomizer or misting nozzle may be used to generatemicro sized droplets (100 to 200 micron size) of an incompressiblefluid. The generation of micro sized droplets can create a large surfacearea for absorption and small diffusion distance for an efficientabsorption of oxygen from the compressible feed stream into theincompressible fluid. The interfacial area available for contact betweenthe incompressible fluid droplets and oxygen can be around 40,000 m²/m³of mixing space. The volumetric incompressible fluid phase mass transfercoefficient can be 7 to 8 s⁻¹. This can be an order of magnitude higherthan conventional contacting towers.

Industrial atomizer or misting nozzle designs can be based on eitherhigh pressure incompressible fluid (e.g., a liquid) or they can be basedon a gas assist nozzle design. In high-pressure liquid nozzles, theincompressible fluid pressure is used to accelerate the incompressiblefluid through small orifices and create shear forces inside nozzlepassages that break down the incompressible fluid into micron sizedroplets. The shear energy is supplied by the high-pressureincompressible fluid and is therefore called a high pressure atomizer.In the case of gas assist atomizer nozzles, the inertial force createdby supersonic gas jets (e.g., air) shears the incompressible fluid jetswhile inside the atomizer nozzle and as the incompressible fluid jetexits the atomizer nozzle, breaking the incompressible fluid jet intomicron size droplets. Industrial atomizers and misting nozzles suitablefor use with the incompressible fluids of the present invention areavailable from Spraying System Co. of Wheaton, Ill.

Industrial atomizers or misting nozzle designs can create either a solidcone spray pattern or a hollow cone spray pattern. Hollow cone spraypatterns can break up incompressible fluids in a shorter distance andare therefore preferred for use with the present invention. The nozzleorifice size and spraying angle are designed based on incompressiblefluid flow capacities and pressure drop across the nozzle.

The compressible feed stream is combined in a substantially co-currentflow with the incompressible fluid stream and passed through aseparation device in order to at least partially separate oxygen fromthe non-target component(s) of the compressible feed stream. Thedistance between the point at which the compressible fluid feed streamis combined with the incompressible fluid and the entrance of theseparation device provides contact space for oxygen to absorb into theincompressible fluid. The distance between the incompressible fluidinjection point and the separation section of the separation device canbe adjusted to provide for a desired contact time.

In an embodiment as shown in FIG. 2, the separation device 204 is acentrifugal force separator. The centrifugal force separator 204generally has an inlet or throat section 216, a swirl inducing structure218 for imparting a rotational velocity component to the mixedincompressible fluid stream and the compressible feed stream and at thesame time enhancing absorption of oxygen contained in the compressiblefeed stream 202 into the incompressible fluid, a separation section 220for removing any incompressible fluid or solid components from the mixedstream, and a diffuser section 228. An incompressible fluid injectionnozzle 209 for injecting a fine mist of incompressible fluid 208 intothe compressible feed stream 202 may be located within the separationdevice in some embodiments. For example, the incompressible fluidinjection nozzle may be located between the throat section and the swirlinducing structure. Alternatively, the incompressible fluid injectionnozzle or optionally a plurality of incompressible fluid injectionnozzles are located within the separation section of the separationdevice downstream of the swirl inducing structure. In some embodiments,the incompressible fluid injection nozzle 209 can be located upstream ofthe separation device 204. In some embodiments, the incompressible fluidinjection nozzle 209 can be located within the swirl inducing structureor even downstream of the swirl inducing structure. The separationsection 220 of the separation device 204 may include a collection space226 for collecting any separated incompressible fluid from theseparation device 204.

The throat section 216, if included in the separation device, generallyserves as an inlet for the compressible feed stream, which may be mixedwith the incompressible fluid stream, prior to the compressible feedstream entering the separation section of the separation device 204. Ingeneral, the compressible feed stream will enter the separation device204 and throat section 216 at subsonic speeds. In general, the throatsection 216 serves to impart an increased linear velocity to thecompressible feed stream and its components (e.g. the first and secondcompressible components) or the mixed stream prior to passing thecompressible feed stream or mixed stream through the separation device.In some embodiments, the throat section comprises a converging section,a narrow passage, and a diverging section through which the compressiblefeed stream or mixed stream passes. Some embodiments may not have allthree sections of the throat section depending on the fluid flowconsiderations and the desired velocity profile through the separationdevice. The converging section and narrow passage can impart anincreased linear velocity to the compressible feed stream or mixedstream as it passes through. In some embodiments, the throat sectionserves as an inlet section and does not contain a converging passagewayor throat. In an embodiment, the throat section 216 is upstream of theswirl inducing structure such that the compressible feed stream or mixedstream passes through the throat section and then through the swirlinducing structure prior to reaching the separation section of thedevice. However, the swirl inducing structure can be located within thenarrow passage of the throat section in order to impart a rotationalvelocity to the compressible feed stream or mixed stream prior to theincreasing the velocity of the compressible feed stream or mixed streamin the diverging section of the throat section. In another embodiment,the swirl inducing section can be annular or ring shaped with a conicalshape solid section in the center for smooth transition of thecompressible feed stream or mixed stream leaving the throat section andpassing over the swirl inducing structure.

The throat section may increase the linear velocity of the mixed stream,and may increase the velocity of at least the compressible components toa supersonic velocity or a transonic velocity, or the velocity of themixed stream may remain subsonic. The linear velocity and/or theresultant velocity of the compressible feed stream, the incompressiblefluid stream, the mixed stream—including the compressible andincompressible components of the mixed stream—and the first compressibleproduct stream can be described in terms of a Mach number. As usedherein, the Mach number is the speed of an object (e.g. the compressiblefeed stream, the incompressible fluid stream, the mixed stream and/orcomponents thereof, and/or the first compressible product stream) movingthrough a fluid (e.g. air) divided by the speed of sound in the fluid.The flow regimes that may be obtained through the separation device canbe described in terms of the Mach number as follows: subsonic velocityis a Mach number less than 1.0, transonic velocity is a Mach numberranging from 0.8 to 1.2, and supersonic is any velocity greater than 1.0and generally greater than 1.2. The specific design of the throatsection along with the compressible feed stream properties (e.g.,temperature, pressure, composition, flowrate, etc.) will, at least inpart, determine the flow regime of the stream exiting the throat sectionand the corresponding Mach number. In an embodiment, the compressiblefeed stream or the mixed stream exiting the throat section will have aflowrate with a Mach number of greater than 0.1, or alternatively,greater than 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0. In anembodiment, the mixed stream or the compressible feed stream enteringthe separation section of the separation device may have a flowrate witha Mach number may have a flowrate with a Mach number of greater than0.1, or alternatively, greater than 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8,0.9, or 1.0.

In an embodiment, the compressible components in the mixed stream, e.g.the first and second compressible components from the compressible feedstream, may have a Mach number that is different from the Mach number ofthe incompressible fluid in the mixed stream. For example, one or moreof the compressible components in the mixed stream may have a supersonicMach number while the incompressible fluid in the mixed stream has asubsonic Mach number. One or more of the compressible components of themixed stream may have a Mach number of greater than 0.1 or 0.2, 0.3,0.4, 0.5, 0.6, 0.7, 0.8. 0.9. 1.0. 1.1, 1.2, or 1.3. Independently, theincompressible fluid in the mixed stream may have a Mach number of atleast 0.1, or 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8. 0.9, or 1.0.

As noted above, the swirl inducing structure imparts a rotationalvelocity component to the mixed stream containing the compressible feedstream and the incompressible fluid stream. As the mixed stream entersthe separation device 204, its velocity may be substantially linear. Asshown in FIG. 2, a swirl inducing structure 218 is placed in theinternal passageway of the separation device.

In another embodiment, the swirl inducing structure may be placed withinthe narrow passage of the throat section or downstream of the throatsection as a ring or annular shape with solid conical shape in thecenter.

The swirl inducing structure may also increase the linear velocity ofthe compressible components of the mixed stream (e.g. oxygen and asecond compressible component from the compressible feed stream)relative to the linear velocity of the compressible components enteringthe swirl inducing structure. The swirl inducing structure may beconfigured having a curved diverging structure to increase the linearvelocity of the compressible components of the mixed stream whileimparting a rotational velocity component to the mixed stream.

The swirl inducing structure 218 may be any suitable structure, or anymethod may be used for imparting a swirl, so long as a rotationalcomponent is imparted to the mixed stream comprised of the compressiblefeed stream and the incompressible fluid stream. The swirl inducingstructure 218 imparts a rotational velocity component to the flow of themixed stream causing a vortex to form, where the magnitude of therotational velocity component is a function of the geometry of the swirlinducing structure. This may include the angle of the static guidevanes, or the specific geometry of a wing placed in the flow path.Suitable swirl inducing structures can include, but are not limited to,static guide vanes, wing like structures, structures containing one ormore sharp edges, deflection vanes for generating vortices (e.g.,V-shape, diamond shape, half delta, chevrons), and curvilinear tubes(e.g., helical tubes). In an embodiment, the swirl inducing structuremay impart a rotational velocity to the gas ranging from 500 revolutionsper minute (“rpm”) to 30,000 rpm.

In some embodiments, the swirl inducing structure can comprise one ormore incompressible fluid injection nozzles. In some embodiments, theincompressible fluid injection nozzles can be located within the swirlinducing structure. For example, if a wing is used as the rotationalflow inducing structure, the incompressible fluid injection nozzles canbe located on the trailing edge of the wing so that the incompressiblefluid is mixed with the compressible feed stream through the turbulentflow off the wing. In some embodiments, the incompressible fluidinjection nozzle can be oriented to impart a rotational velocitycomponent to the compressible feed stream in addition to the rotationalvelocity component imparted by the swirl inducing structure.

In another embodiment (not shown in FIG. 2), the swirl inducingstructure may comprise one or more inlet stream injection devices forabruptly changing the direction of the mixed stream or the compressiblefeed stream. In this embodiment, one or more incompressible fluidinjection nozzles can be oriented such that the incompressible fluid isinjected into the compressible feed stream at an angle relative to thelinear velocity of the compressible feed stream. The resulting mixedstream will have a rotational velocity component primarily based on theangle of injection and the velocity at which the incompressible fluid isinjected into the compressible feed stream, and will have a linearvelocity component primarily based on the linear velocity of thecompressible feed stream. The resultant velocity with rotational andlinear velocity components will depend, inter alia, on the angle atwhich the incompressible fluid is injected into the compressible feedstream, the velocity of the incompressible fluid exiting theincompressible fluid injection nozzle(s), the velocity of thecompressible feed stream, and the relative flow rates of theincompressible fluid stream and the compressible feed stream.

While not intending to be limited by theory, the rotational motion ofthe mixed stream in the separation section induces a centrifugal forcethat results in the separation of the incompressible fluid and anycompressible target components absorbed therein from the compressiblecomponents within the mixed stream. The incompressible fluid, along withany compressible target components therein, is separated from thecompressible components of the mixed stream that are not absorbed intothe incompressible fluid due to inertial effects and the large densitydifference between the incompressible fluid and the compressiblecomponents not absorbed in the incompressible fluid. Centrifugal forcealso acts on the compressible components so that a pressure gradient iscreated and is represented for a component i by equation 1.P _(i)(r)=P _(i)(0)exp(A _(i) r ²)  (Eq. 1)

where Pi is the partial pressure of component i (MPa), P_(i)(0) is theinitial pressure at the center of the device, and r is the radialcoordinate in meters (m). The coefficient A_(i) is defined according toequation 2.A _(i)=(MW _(i)Ω²)/(2RT)  (Eq. 2)

where MW_(i) is the molecular weight of component i, Ω is the angularvelocity, R is the gas constant, and T is the temperature. Thisrelationship demonstrates how the pressure changes as a function ofradius. The coefficient A_(i) increases at higher speeds and forcompressible components with higher molecular weights.

The mixed stream 202 & 208 in the separation device 204 passes throughthe swirl inducing structure causing the mixed stream to rotate throughthe remainder of the separation device. The swirl inducing structuregenerally maintains the flow regime of the entering compressible feedstream or mixed stream. For example, given a supersonic linear velocityof the compressible components passing through the swirl inducingstructure, the compressible component velocity would retain a supersoniclinear velocity. For an incompressible fluid or compressible componentsentering the swirl inducing structure with a subsonic linear velocity,the linear component of the velocity would generally remain subsonic. Asdescribed above, however, the swirl inducing structure may be configuredto increase the linear velocity of the compressible components and/orthe incompressible fluid, and may change the flow regime of thecompressible components and/or incompressible fluid.

While not intending to be limited by theory, it is believed that a highrate of mass transfer of oxygen and any other compressible targetcomponent(s) between the compressible feed stream and the incompressiblefluid takes place in the swirl inducing structure. As the mixed streampasses through the swirl inducing structure, intimate mixing is achievedbetween the incompressible fluid droplets and the compressiblecomponents from the compressible feed stream. The mass transfer ratebetween the incompressible fluid droplets and the compressiblecomponents will be proportional to the surface area of the droplets. Assuch, smaller droplets will tend to show greater mass transfer rateswithin the swirl inducing structure. The fluid mixture leaving the swirlinducing structure should be at or near equilibrium between theincompressible fluid droplets and oxygen from the compressible feedstream. The removal of the droplets in the downstream separation sectionthen removes oxygen and any other compressible target components fromthe compressible non-target components of the compressible feed stream.

The separation device has a separation section 220 for removing anyincompressible fluid or the majority of the incompressible fluidcontained in the mixed stream. As described above, removing anincompressible fluid or a portion thereof from the mixed streamseparates a constituent from the mixed stream, where the constituent isselected from the group consisting of a mixture of oxygen and theincompressible fluid, a product or an adduct of a reaction betweenoxygen and the incompressible fluid, and mixtures thereof.

The separation section may include structures for the extraction ofparticles and the incompressible fluid from the mixed stream. Variousstructures and arrangements may be utilized for extracting particles andthe incompressible fluid from the mixed stream while maintaining thefluid flow through the separation device. In an embodiment, an innerconduit 222 having openings or passages disposed therein may be disposedwithin an outer conduit 224. The inner conduit has a geometry that canbe chosen so as to determine the flow pattern within the separationdevice, as described in more detail below. In the separation section,the heavier components, which include the incompressible fluid in whichthe oxygen is absorbed or mixed, solid particulates, if any, and heaviercompressible components, may move radially outward towards the innersurface of the inner conduit 222. Upon contacting the conduit, theincompressible fluid may form a film on the inner surface of the conduitand migrate through the openings in the inner conduit to the annularspace 226 between the inner conduit 222 and the outer conduit 224. In anembodiment, the size of the openings may be selected such that anincompressible fluid film forms on the inner surface of the innerconduit so as to prevent any compressible component within theseparation section, other than one absorbed by or reacted with theincompressible fluid, from passing to the annular space between theinner and outer conduits. As a further absorption mechanism, thebuild-up of the heavier gas components along the inner surface of theinner conduit may increase the concentration of the heavier compressiblecomponents in contact with the incompressible fluid. If the heaviercompressible components are soluble in or react with the incompressiblefluid, additional absorption may occur due to the higher partialpressure of the heavier compressible components in contact with theincompressible fluid. The incompressible fluid containing oxygen thenmigrates through the openings in the inner conduit and builds up in theannular space for removal through one or more drain ports 230.

In an embodiment, the annular space may contain partitions to allow forthe removal of the incompressible fluids from specific subsections ofthe separation section. For example, the annular space may bepartitioned into a plurality of subsections, each containing a dedicateddrain port. Such a configuration may allow the removal of any solids inthe section nearest the inlet, followed by the incompressible fluidenriched in heavier compressible components, and finally followed by theincompressible fluid enriched in lighter gases. The addition ofindividual drain ports for each subsection allows for separateprocessing of these streams to optimize the target component recoverywhile minimizing the energy consumption of the process.

In another embodiment, one or more incompressible fluid nozzles may bedisposed within the separation section. Such an arrangement may beuseful in combination with partitions within the annular space. In thisembodiment, an incompressible fluid may be injected and then removedprior to injection of additional incompressible fluid in the downstreamdirection. The injected incompressible fluid may be the same in eachinstance or it can be different. Thus, specific components can betargeted throughout the separation section using differentincompressible fluids with discrete drain ports for removing theinjected incompressible fluid from each section.

In an embodiment, the geometry of the separation section may take avariety of shapes. In general, higher rotational velocities result inbetter separation of the incompressible fluid. Thus, a separationsection with a converging profile can result in a higher separationefficiency but a diverging section may have greater pressure recoveryfor the first compressible product stream. A cylindrical sectionbalances separation efficiency and pressure recovery by maintaining thetangential and linear velocities, which may decrease through theseparation section due to drag forces.

As shown in FIG. 2, the flow of the mixed stream through the separationsection may take place within an inner conduit comprising a convergingflow profile (i.e., the diameter of the gas flow channel in theseparation section decreases along the flow axis in the direction offlow). In this configuration, the linear velocity component of the mixedstream and its components may diminish with the decrease in the radiusof the inner conduit due, at least in part, to the absorption of thetarget component in the incompressible fluid. Where the linear velocitycomponent of the mixed stream decreases and the rotational velocityremains the same (or decreases to a smaller degree), the swirl ratiodefined as V_(rotational)/V_(linear) increases. An increase in the swirlratio can enhance or enforce the centrifugal force of the separation,thus increasing the efficiency of separation of the incompressible fluidcontaining the oxygen and the removal efficiency of particles of smalldiameter from the mixed stream.

In another embodiment, the separation section may have a diverging flowprofile within the inner conduit in the separation section. As a fluidflow phenomena, when a fluid with a subsonic velocity passes through aconduit with an increasing diameter, the linear velocity will decrease.However, when a fluid at supersonic flow (Mach number >1) enters adiverging conduit, the linear velocity will increase. This process maybe used to generate a mixed stream flow, or a flow of at least thecompressible components of the mixed stream, through the separationdevice with a supersonic velocity, which may be desired in someembodiments.

In an embodiment, the conduit may maintain a constant diameterthroughout the separation section. The resulting velocity profile of themixed stream should remain the same or nearly the same throughout theseparation section until the compressible components of the mixed streamthat are not absorbed by the incompressible fluid approach the diffuser228, where the non-absorbed compressible components may undergo adecrease in velocity.

Although the linear velocity of the mixed stream, including the second(non-target) compressible component from the compressible feed stream,may decrease through the separation section depending on theconfiguration of the separation section, the linear velocity of thesecond compressible component is increased at some point in the processrelative to the initial linear velocity of the second compressiblecomponent in the compressible feed stream. The linear velocity of thesecond compressible component is increased relative to the initiallinear velocity of the second compressible component in the compressiblefeed stream by momentum transfer imparted by mixing the incompressiblefluid stream with the compressible feed stream in a substantiallyco-current flow to form the mixed stream and/or by passing through theswirl inducing structure. Furthermore, although the linear velocity ofthe second compressible component of the compressible feed stream isincreased upon mixing with the incompressible fluid stream and/or bypassing through the swirl inducing device, the linear velocity of themixed stream, including the second compressible component, may decreasein the separation section, and the overall linear velocity of the secondcompressible component from the compressible feed stream may decreaserelative to the initial linear velocity of the second compressiblecomponent in the compressible feed stream depending on the configurationof the separation section.

Selection of the shape of the separation section depends on theproperties of the target component(s), the conditions of thecompressible feed stream, the concentrations of the components in thecompressible feed stream and desired in the product streams, the type ofincompressible fluid used, and the expected rotational rate of the mixedstream flowing through the separator. For example, a diverging flowprofile may be used to generate a supersonic compressible componentvelocity through the separation section. Such a design may modify thefluid conditions to improve solubility of oxygen and any othercomponents to be separated in the incompressible fluid. For example, ifwater vapor is to be removed from a compressible feed stream, theseparation section design may be chosen so that the fluid conditionsresult in the liquification or near liquification of water at or nearthe inner surface of the inner conduit. Such an embodiment shouldincrease the water loading in the incompressible fluid, if any ispresent. Other effects may be achieved based on thermodynamicconsiderations.

In an embodiment, a diffuser is used to decelerate the compressibleproduct stream passing through the inner conduit once the incompressiblefluid including oxygen and any other incompressible components has beenremoved. A diffuser generally has a divergent shape, which may bedesigned based on the expected flow regime of the compressible productstream passing through the inner conduit. If a supersonic compressibleproduct stream velocity is expected through the inner conduit, thediffuser may be designed to establish a controlled shock wave. For otherflow velocities, the diffuser may be used to return the compressibleproduct stream to a primarily linear velocity with a correspondingincrease in pressure for use in downstream processes. In general, thepressure of the compressible product stream passing through the innerconduit will increase upon passing through the diffuser.

In an embodiment, other equipment can be included downstream of theseparator device to further process the first compressible productstream 206. For example, further incompressible fluid removal equipmentmay be used to remove any entrained incompressible fluid droplets in thefirst compressible product stream that are not separated in theseparation section of the separation device. For example, a polishingdevice that induces a change in the direction of flow of the firstcompressible product stream can be used to cause the entrainedincompressible fluid to impinge on a surface and coalesce forcollection. Suitable polishing devices can include, but are not limitedto, a vane type separator, and a mesh type demister. Additional furtherincompressible fluid removal equipment can include, but is not limitedto, membrane separators. In an embodiment, a heat exchanger is used tocool the first compressible product stream and induce condensation ofany incompressible fluids entrained in the first compressible productstream prior to the first compressible product stream entering theincompressible fluid removal equipment.

Solvent Recovery and Regeneration (Other Equipment)

In an embodiment, an incompressible fluid recovery process may be usedto regenerate the incompressible fluid for reuse within the process andto recover the oxygen. Referring to FIG. 2, the incompressible fluidproduct stream 212 leaving the drain port 230 contains theincompressible fluid removed from the separation device 204 along withoxygen and, optionally, at least one additional target component. Inorder to regenerate the incompressible fluid for recycle to theincompressible fluid inlet to the separation device (e.g. nozzle 209),the incompressible fluid is regenerated using a incompressible fluidseparation device 210. The incompressible fluid separation device may beany device capable of separating at least some of the oxygen from theincompressible fluid product stream. The design of the incompressiblefluid separation device will depend on the target component composition,the type of incompressible fluid used in the separation device, and theloading of the target component in the incompressible fluid.

In an embodiment in which the incompressible fluid is a physical solventsuch as a fluorinated compound, a simple separation device comprising astripping vessel, a flash tank, or a distillation column (e.g., aselective distillation column) may be used to remove the oxygen from theincompressible fluid product stream. Such a separation device mayfunction by heating the oxygen rich incompressible fluid product stream(e.g., temperature swing separation) or reducing the pressure of theoxygen rich incompressible fluid product stream (e.g., pressure swingseparation), thus reducing the oxygen solubility in the incompressiblefluid. In some embodiments, steam or another suitable heat source may beused in a direct heat transfer system to increase the temperature of theincompressible product stream. The oxygen can be separated as a secondcompressible product stream in the gas phase through an overhead stream214 and passed on to further downstream processes.

The oxygen-depleted incompressible fluid (the “regeneratedincompressible fluid”) may be passed back to the incompressible fluidinjection nozzle 209 at the inlet of the separation device. Theincompressible fluid removed from the incompressible fluid separationdevice 210 may contain some of the oxygen when recycled to theincompressible fluid injection device, depending on the conditions ofthe incompressible fluid separation device. Such minor amounts can beexpected based on the design of the system and should not affect theremoval efficiency of the overall separation method described herein.

In an embodiment in which the incompressible fluid is a chemicalsolvent, the incompressible fluid separation device may incorporate aheating source for breaking any chemical compounds or adducts that areformed between the original incompressible fluid and the oxygen. Forexample, a reactive distillation scheme can be used to remove the oxygenfrom the incompressible fluid product stream. The heating source can beany direct or indirect heat source, for example steam. If direct heatingis used, the heating source (e.g., steam) may pass out of theincompressible fluid separation device along with the oxygen and beremoved in a flash tank downstream. Water separated in this fashion maybe discarded or it can be recycled to a boiler or other heating sourcefor reuse within the process.

In an embodiment shown in FIG. 6, the incompressible fluid productstream 112 leaving the drain port contains the incompressible fluidremoved from the separation device along with at least oxygen. Theincompressible fluid separation device 110 comprises any suitableseparation device such as a fractional distillation column containingmultiple trays or plates to allow for vapor-liquid equilibrium. In thisembodiment, the incompressible fluid product stream 112 is heated toseparate the oxygen into the gas phase. A condenser 608 cools theseparated gas phase containing oxygen and results in a compressibleoxygen product stream 609 and a liquid product stream 602, a portion ofwhich is returned to the incompressible fluid separation device to allowfor proper separation of the components in the separation device 110.The incompressible fluid with at least a portion of the oxygen removedis removed from the bottom of the column as a liquid stream 108. Otheroptional outlet streams can leave the incompressible fluid separationdevice 110 as liquid streams 604, 606. For example, any water present inthe incompressible fluid product stream 112 entering the incompressiblefluid separation device 110 can optionally be removed as a liquid stream606 for further use within the process as desired. The incompressiblefluid separation device 110 can be operated at a temperature andpressure sufficient to generate liquid outlet streams. One of ordinaryskill in the art with the benefit of this disclosure would know theconditions to generate liquid outlet streams.

Specific Embodiments

FIG. 3 schematically illustrates another embodiment of a separationprocess and system for removing oxygen and, optionally, one or moreadditional compressible target components from a compressible feedstream using an incompressible fluid. In this embodiment, a compressiblefeed stream 302, which may be an air stream for example, is first passedthrough an expander 304. The compressible feed stream 302 is at apressure ranging from 2 bar (0.2 MPa) to 200 bar (20 MPa). The resultingexpansion of the compressible feed stream 302 passing through theexpander 304 produces shaft work that is transferred through a commonshaft 306 with a compressor 334 operating downstream of the separationdevice 314.

The expanded compressible feed stream 308 then passes to the inlet ofthe separation device 314. The expanded compressible feed stream 308 iscombined with an incompressible fluid stream 310 by, for example,passing the incompressible fluid 310 through a nozzle 311 to producedroplets which are mixed in the expanded compressible feed stream 308.This mixing is preferably, but not necessarily, effected within theseparation device 314. The resulting mixed stream then passes through athroat section either before or after passing over a swirl inducingstructure 312 that imparts a rotational velocity component to the mixedstream. The mixing of the incompressible fluid droplets with thecompressible feed stream in the swirl inducing structure results inoxygen and any other compressible target components being transferredfrom the compressible feed stream into the incompressible fluid. Thevelocity of the combined mixture is determined by the design of theseparation device and the entering stream properties.

The resulting swirling mixed stream then passes into a separationsection 316 of the separation device 314. The separation section has aninner conduit 318 with openings to allow fluid communication with theannular space between the inner conduit 318 and an outer conduit 320.The incompressible fluid droplets are then separated from a compressibleproduct stream due to the centrifugal force of the swirling fluid flowin the separation section. The incompressible fluid droplets impinge onthe inner surface of the inner conduit 318 to form an incompressiblefluid film. The compressible product stream separated from theincompressible fluid exits the separation section 316 and enters adiffuser section 324 before exiting the separation device as the firstcompressible product stream 332. The first compressible product streampasses through the compressor 334 that is on the common shaft 306 withthe inlet expander 304. As the first compressible product stream 332passes through the compressor 334 the pressure of the resultingcompressible stream 336 is increased. The pressure of the firstcompressible product stream can be measured at a location at or near theoutlet of the separation device 314, as described in more detail below.

In an embodiment, the incompressible fluid separated from thecompressible product stream in the separation section 316 of theseparation device 314 collects in the annular space between the innerconduit 318 and the outer conduit 320 before being removed through adrain port 322. The flow rate out of the separation device 314 throughthe drain port 322 may be controlled so that an incompressible fluidfilm is maintained on the inner surface of the inner conduit 318. Theliquid film prevents the components of the compressible product streamthat are not absorbed or mixed in the incompressible fluid from passingthrough the openings in the inner conduit 318 and passing out of theprocess through the drain port 322. The resulting oxygen richincompressible fluid product stream 326 then passes to a incompressiblefluid regeneration system. In an embodiment, a pump 328 can be suppliedto increase the pressure of the oxygen rich incompressible fluid 330 forsupply to the incompressible fluid regeneration system. Once theincompressible fluid is regenerated, it may be recycled to be used asthe incompressible fluid 310 for the process. In another embodiment, theincompressible fluid 310 used at the incompressible fluid inlet is freshincompressible fluid.

Another embodiment of the process and device is schematically shown inFIG. 4. In this embodiment, the incompressible fluid regeneration deviceis a centrifugal separation device. In this embodiment, a compressiblefeed stream 402, which may be a stream of air for example, is firstpassed through a compressor 404 to increase the pressure to a suitableoperating pressure before being cooled in a heat exchanger 405. Thecompressible feed stream 402 may be at a pressure ranging from 2 bar(0.2 MPa) to 200 bar (20 MPa) prior to entering the compressor 404 andat an higher pressure after the compressor 404. In an embodiment, thecompressible feed stream 402 temperature is cooled to near the freezingpoint of the incompressible fluid selected to separate oxygen from thecompressible feed stream to increase the solubility of the oxygen in theincompressible fluid stream.

The compressed, cooled compressible feed stream 408 is fed into theseparation device 414. The compressed, cooled compressible feed stream408 is combined with an incompressible fluid stream 406 to form a mixedstream by, for example, passing the incompressible fluid stream 406through a nozzle 412 to produce droplets and injecting the droplets intothe compressible feed stream. This mixing is preferably, but notnecessarily, effected within the separation device. The resulting mixedstream may be passed through a throat section either before or afterbeing passed over a swirl inducing structure 416 that imparts arotational velocity component to the mixed stream. The mixing of theincompressible fluid droplets with the compressible feed stream in theswirl inducing structure may enhance the transfer of oxygen and,optionally, one or more additional compressible target components fromthe compressible feed stream into the incompressible fluid. The velocityof the combined mixture is determined by the design of the separationdevice and the entering stream properties. The compressible feed streamis at subsonic, transonic, or supersonic velocity while theincompressible fluid stream may be at subsonic velocity, as desired.

In an embodiment, the resulting swirling mixed stream then passes into aseparation section 418 of the separation device 414. The separationsection 418 has an inner conduit 420 with openings to allow fluidcommunication with the annular space between the inner conduit 420 andan outer conduit 422. The incompressible fluid droplets containing theoxygen and optional additional compressible target component(s) areseparated due to the centrifugal force of the swirling flow of the mixedstream in the separation section. The incompressible fluid dropletsimpinge on the inner surface of the inner conduit 420 to form anincompressible fluid film. A compressible stream from which theincompressible fluid and at least a portion of the oxygen and optionaladditional compressible target component(s) have been separated thenexits the separation section 418 and enters a diffuser section 424before exiting the separation device 414 as a first compressible productstream 426. The first compressible product stream may then be used forvarious downstream uses.

The incompressible fluid in which at least a portion of the oxygen hasbeen absorbed that is separated from the mixed stream in the separationsection 418 of the separation device 414 collects in the annular spacebetween the inner conduit 420 and the outer conduit 422 before beingremoved through a drain port 428. The flow rate of the incompressiblefluid out of the separation device 414 through the drain port 428 may becontrolled so that an incompressible fluid film is maintained on theinner surface of the inner conduit 420. The incompressible fluid filminhibits the compressible components in the mixed stream from passingthrough the openings in the inner conduit 420 and passing out of theprocess through the drain port 428 unless the compressible component(s)are target components absorbed in the incompressible fluid. Theresulting oxygen-rich incompressible fluid product stream 430 thenpasses to an incompressible fluid regeneration system. A pump 432 may besupplied to increase the pressure of the oxygen-rich incompressiblefluid product stream for supply to the incompressible fluid regenerationsystem.

In the embodiment shown in FIG. 4, the incompressible fluid regenerationsystem comprises a centrifugal force separator 440. The oxygen-richincompressible fluid product stream 430 is supplied to the centrifugalforce separator 440. A steam feed 442 is fed to the centrifugal forceseparator 440 to provide direct heating of the oxygen-richincompressible fluid. The steam feed 442 is combined with theoxygen-rich incompressible fluid product stream using any known means ofcombining a liquid stream with a gas. For example, the oxygen-richincompressible fluid product stream 430 may be passed through a nozzle444 to produce a microdroplet mist which may be mixed with the steamfeed 442. This mixing is preferably, but not necessarily, effectedwithin the separation device 440. The resulting mixture may then bepassed through a throat section either before or after being passed overa swirl inducing structure 446 that imparts a rotational velocitycomponent to the mixed stream. The mixing of the oxygen-richincompressible fluid droplets with the steam, enhanced by the swirlinducing structure, may result in oxygen, and, optionally one or moreadditional compressible target components, being transferred from theoxygen-rich incompressible fluid product stream into the compressiblegaseous steam. The velocity of the combined mixture is determined by thedesign of the separation device and the entering stream properties. Thecompressible portion of the mixed stream is at subsonic, transonic, orsupersonic velocity as desired.

The resulting swirling mixed stream then passes into a separationsection 448 of the separation device 440. The separation section 448 hasan inner conduit 450 with openings to allow fluid communication with theannular space between the inner conduit 450 and an outer conduit 452.Incompressible fluid droplets are separated from compressible componentsin the mixed stream due to the centrifugal force of the swirling fluidflow in the separation section. The incompressible fluid dropletsimpinge on the inner surface of the inner conduit 450 to form anincompressible fluid film. A compressible target component productstream containing oxygen and optionally one or more target componentsfrom which the incompressible fluid is separated exits the separationsection 448 and enters a diffuser section 454 before exiting theseparation device 440 as a crude compressible target component productstream 456. The crude compressible target component product stream 456may be passed to a separation device 458, for example, a flash tank ordistillation column, to condense any water present in the crudecompressible target component product stream. The separation device 458produces a polished compressible target component product stream whichis the second compressible product stream 460 comprising oxygen and,optionally, any additional target component(s) separated from thecompressible feed stream. In an embodiment, the second compressibleproduct stream passes through a compressor 462 to raise the pressure ofthe second compressible product stream 464 before being passeddownstream for other uses.

The separation device 458 also produces an incompressible fluid stream466 comprising the water from the steam injected into the incompressiblefluid regeneration device 440. In an embodiment, the water is recycledto form the steam that is injected into the separation device orotherwise used in the process.

In an embodiment, the incompressible fluid separated from thecompressible target component product stream in the separation device440 comprises an oxygen-depleted incompressible fluid stream 468 forrecycle to the inlet of the process. In an embodiment, additional water474 and make-up incompressible fluid 472 are added in a mixing vessel470, as required. The oxygen-depleted incompressible fluid may passthrough heat exchanger 469 to adjust the oxygen-depleted incompressiblefluid temperature to the desired temperature of the makeupincompressible fluid. The resulting oxygen-depleted incompressible fluidmixture 476 may be passed through a pump 478 to increase pressure forinjection into the separation device 414 through the incompressiblefluid injection nozzle 412. In an embodiment, the process is repeated tofurther remove oxygen from the compressible feed stream.

FIG. 5 schematically illustrates another embodiment of a separationprocess and system for removing one or more components from acompressible feed stream using an incompressible fluid. This embodimentis similar to the embodiment shown in FIG. 2. In this embodiment, acompressible feed stream 502, which may be an air stream for example, isat a pressure ranging from 2 bar (0.2 MPa) to 200 bar (20 MPa). Thecompressible feed stream 502 is fed to the separation device 504. Thecompressible feed stream 502 is combined with an incompressible fluidstream 508 by, for example, passing the incompressible fluid through anozzle 540 to produce incompressible fluid droplets and mixing theincompressible fluid droplets with the compressible feed stream. Thismixing is preferably, but not necessarily, effected within theseparation device 504. The resulting mixed stream may then be passedthrough a throat section either before or after being passed over aswirl inducing structure 518 for imparting a rotational velocitycomponent to the mixed stream and its components. The mixing of theincompressible fluid droplets with the compressible feed stream,enhanced by the swirl inducing structure, results in oxygen beingtransferred into the incompressible fluid. The velocity of the mixedstream is determined by the design of the separation device and theentering stream properties.

The resulting swirling mixed stream is then passed into a separationsection 520 of the separation device 504. The separation section has aninner conduit 522 with openings to allow fluid communication with theannular space 526 between the inner conduit 522 and an outer conduit524. Oxygen-enriched incompressible fluid droplets may be separated fromthe mixed stream due to the centrifugal force of the swirling flow ofthe mixed stream in the separation section. The oxygen-enrichedincompressible fluid droplets impinge on the inner surface of the innerconduit 522 to form an incompressible fluid film. A compressible productstream formed by separation of the oxygen-enriched incompressible fluidfrom the mixed stream then exits the separation section 520 and enters adiffuser section 528 before exiting the separation device 504 as a firstcompressible product stream 506.

In an embodiment, the first compressible product stream 506 passesthrough an additional incompressible fluid separator 542 to remove anyremaining incompressible fluid contained in the first compressibleproduct stream 506 to form a polished first compressible product stream544. In an embodiment, the incompressible fluid separator 542 comprisesany device capable of removing incompressible fluid droplets from thefirst compressible product stream. For example, incompressible fluidseparators can include, but are not limited to, vane separators,settling tanks, membranes, and mesh type demisters. The resultingpolished first compressible product stream 544 may pass to a compressor546. As the polished first compressible product stream 544 passesthrough the compressor 546 the pressure of the resulting compressiblestream 548 may be increased. The incompressible fluid 552 removed fromthe first compressible product stream 506 in the incompressible fluidseparator 542 may be combined with regenerated incompressible fluid fromthe incompressible fluid regenerator device 510. In an embodiment, theincompressible fluid stream 552 passes through a pump 550 to provide thedriving force to move the incompressible fluid through the associatedpiping.

The oxygen-enriched incompressible fluid separated from the mixed streamin the separation section 520 of the separation device 504 collects inthe annular space 526 between the inner conduit 522 and the outerconduit 524 before being removed through a drain port 530. The flow rateof the oxygen-enriched incompressible fluid out of the separation device504 through the drain port 530 may be controlled so that anincompressible fluid film is maintained on the inner surface of theinner conduit 522. The incompressible fluid film inhibits compressiblecomponents of the mixed stream that are not absorbed in theincompressible fluid from passing through the openings in the innerconduit 522 and passing out of the process through the drain port 530.The oxygen-enriched incompressible fluid stream 512 removed from theseparation device may be passed to a incompressible fluid regenerationdevice 510 for separation of oxygen from the incompressible fluid andfor regeneration of the incompressible fluid. Once the incompressiblefluid is regenerated, it may be recycled for re-use in the separationdevice 504. In an embodiment, the recycled incompressible fluid can bepassed through a heat exchanger 515 to provide an incompressible fluidat a desired temperature to the separation device 504. In anotherembodiment, the incompressible fluid 508 used at the inlet of theseparation device 504 is fresh incompressible fluid.

The incompressible fluid regeneration device 510 removes oxygen absorbedin the incompressible fluid 508 as a compressible stream 514. Thisstream 514 is the second compressible product stream which exits theincompressible fluid regeneration device 510 for utilization in any ofthe end uses of the products discussed herein.

Energy Balance Description

In an embodiment, the present invention provides a process and devicefor separating oxygen from a compressible feed stream with a lowerenergy input requirement than conventional separation processes.Specifically, the use of a separation process as described hereinutilizes less energy to separate a compressible component from acompressible feed stream containing at least two compressible componentsthan conventional processes, for example, cryogenic processes andmembrane separation units.

One way to examine this energy consumption is to view the energyconsumed in the process relative to the chemical energy content of thefeed stream, as described in more detail below.

In calculating an energy consumption around any separation process,several forms of energy are taken into account. In general, an energyconsumption calculation accounts for heat flow in or out of a system orunit, shaft work on or by the system, flow work on or by the system thatmay be taken into account through a calculation of the change inenthalpy of all of the streams entering or leaving a system, and changesin the kinetic and potential energy of the streams associated with asystem. The energy balance will generally take into account the energyrequired by each unit in the system separately unless the energy flowsof a unit are tied to another unit, for example, in a heat integrationscheme. When comparing two processes, any difference in the enthalpy ofentering streams (e.g., due to differences in temperature or pressure)can be calculated and taken into account in the energy consumptioncalculation during the comparison. In addition, a comparison betweenvarious systems should take into account all process units involving anystream between the inlet measurement point and the outlet measurementpoints. Any use of any stream or portion of a stream as fuel for thesystem should be taken into account in the energy consumptioncalculation. In an embodiment, a process simulator or actual processdata may be used to calculate the energy requirements of each unit of aspecific process. Common measures of energy consumption from processcalculations include heating and cooling loads, steam supplyrequirements, and electrical supply requirements.

As a common measurement location, an energy consumption calculationshould take into account a feed stream immediately prior to entering theseparation process. The product streams should be measured at the firstpoint at which each product stream is created in its final form. Forexample, in FIG. 2, the feed stream 202 would be measured immediatelyprior to entering the separation device 204 and being combined with theincompressible fluid 208. The first compressible product stream 206would be measured immediately upon exiting the separation device 204,which would be just downstream of the diffuser 228. The secondcompressible product stream would be measured at the first point atwhich the separated target component stream is removed from theincompressible fluid. This would be just downstream (e.g., at the exit)of the incompressible fluid regeneration device 210.

Other separation processes have similar stream locations that define theboundary of which units are included in an energy balance. For example,a distillation column would have an inlet stream that would be measuredjust prior to entering the distillation column. The overhead outletstream and the bottoms outlet stream would represent the two outletstream measurement points. All of the units in between the these threepoints would be considered in the energy consumption calculation. Forexample, any reboilers, condensers, side stream units, side streamrectifiers, or other units found in the distillation sequence would beconsidered.

Conventional processes for separating oxygen from a compressible feedstream such as air can consume more than 1,500 Btu/lb-oxygen removed. Inan embodiment, the energy consumption of the systems and methodsdisclosed herein is less than 1,200 Btu/lb-oxygen removed, oralternatively, less than 1,000 Btu/lb-oxygen removed.

Pressure Effects within the Separator

The use of the separation process and device of the present inventioncan be described in terms of the pressure differentials between the feedand compressible product streams. As a common measurement location, thecompressible feed stream pressure may be measured near the compressiblefeed stream inlet to the separation device. In an embodiment in which anexpander is used prior to the separation device and a compressor is usedafter the separation device, each of which may share a common shaft, thecompressible feed stream pressure may be measured near the inlet of theexpander. The compressible product streams should be measured at thefirst point at which the product stream is created in its final form.For example, in FIG. 2, the compressible feed stream 202 pressure wouldbe measured near the entrance to the separation device 204 prior to thecompressible feed stream being combined with the incompressible fluid208. The first compressible product stream 206 would be measured nearthe exit of the separation device 204, which would be just downstream ofthe diffuser 228. The second compressible product stream would bemeasured at the first point at which the separated target componentstream is removed from the incompressible fluid. This would be justdownstream (e.g., near the exit) of the incompressible fluidregeneration device 210. In an embodiment in which the secondcompressible product stream leaves the incompressible fluid regenerator,and thus the overall separation process as a liquid, the pressure of thesecond compressible product stream can be measured at the point at whichthe compressible component is compressible within the incompressiblefluid separation device. For example, the equilibrium vapor pressure atthe point in the separation device at which the compressible componentis a gas or vapor can be used to measure the second compressible productstream pressure. For example, the conditions above a tray in the columncan be taken as the common measurement location in this embodiment. Thispoint may also be used for the energy balance described herein.

In an embodiment of the invention, the pressure differentials betweenthe feed and compressible product streams will be less than conventionalseparation processes. This is advantageous because it avoids orminimizes the need to repressurize the compressible product streams forthe next use or application. In an embodiment, the compressible feedstream pressure will be within 50% of each compressible product streampressure. In another embodiment, the compressible feed stream pressurewill be within 40% of each compressible product stream pressure. In anembodiment, the compressible product stream pressures will be within 20%of one another. For example, in an embodiment with two compressibleproduct streams, the pressure of the first compressible product streamwill be within 20% of the second compressible product stream pressure.In another embodiment, the compressible product stream pressures may bewithin 15% of one another.

End Uses of Output Streams

The compressible product streams produced by the method and device ofthe present invention may be used for a variety of purposes. In anembodiment, two compressible product streams are produced. The firstincludes the components of the compressible feed stream that passthrough the diffuser of the separation device. The second includesoxygen that is removed from the compressible feed stream. Each streammay be used for further downstream uses depending on the streamcomposition and properties.

In an embodiment in which the compressible feed stream is a stream ofair, the compressible product streams may comprise a first streamenriched in nitrogen, and a stream enriched in oxygen. A plurality ofseparation processes can be used in series to generate a nitrogen and/oroxygen stream with a desired level of purity. The stream enriched innitrogen and the stream enriched in oxygen can be sold as industrialgases. For example, the stream enriched in oxygen can be used as areactant in a variety of chemical reactions including as a feed to anoxy-fuel combustion process.

In another embodiment, a product stream may be fed to a separationprocess for further processing. For example, the process and methodsdescribed herein may be used to produce a product stream that becomes afeed stream to a conventional separation process, such as a cryogenicseparation process. The use of the process and methods described hereinmay reduce the energy consumption of the combined processes and increasethe efficiency of the overall separation.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present invention. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps. Allnumbers and ranges disclosed above may vary by some amount. Whenever anumerical range with a lower limit and an upper limit is disclosed, anynumber and any included range falling within the range is specificallydisclosed. In particular, every range of values (of the form, “fromabout a to about b,” or, equivalently, “from approximately a to b,” or,equivalently, “from approximately a-b”) disclosed herein is to beunderstood to set forth every number and range encompassed within thebroader range of values. Also, the terms in the claims have their plain,ordinary meaning unless otherwise explicitly and clearly defined by thepatentee. Moreover, the indefinite articles “a” or “an”, as used in theclaims, are defined herein to mean one or more than one of the elementthat it introduces.

What is claimed is:
 1. A method comprising: providing a compressible feed stream comprising a first compressible component and a second compressible component, where the first compressible component is oxygen; providing an incompressible fluid stream comprised of an incompressible fluid capable of absorbing oxygen or reversibly reacting with oxygen; mixing the compressible feed stream and the incompressible fluid stream to form a mixed stream, where the compressible feed stream is provided for mixing at a first linear velocity in a first direction and the incompressible fluid stream is provided for mixing at a second linear velocity in a second direction, the second linear velocity having a velocity component in the same direction as the first direction, where the mixed stream has an instantaneous third linear velocity in a third direction and is comprised of the second compressible component and a constituent selected from the group consisting of a mixture of the oxygen and the incompressible fluid, a chemical compound or adduct of a reversible reaction between the oxygen and the incompressible fluid, and mixtures thereof; imparting a rotational velocity to the mixed stream, where the direction of the rotational velocity is tangential or skew to the direction of the instantaneous third linear velocity of the mixed stream; and separating an incompressible fluid product stream from the mixed stream, where the incompressible fluid product stream contains at least a portion of the constituent of the mixed stream, and where the incompressible fluid product stream is separated from the mixed stream as a result of the rotational velocity imparted to the mixed stream.
 2. The method of claim 1 further comprising the step of separating a first compressible product stream comprising the second compressible component from the mixed stream.
 3. The method of claim 1 wherein the mixed stream has a resultant velocity or a linear velocity with a Mach Number of greater than 0.1 at some point in the step of separating the incompressible fluid product stream from the mixed stream.
 4. The method of claim 1 further comprising the step of selecting the incompressible fluid, wherein the incompressible fluid is selected to selectively absorb oxygen or react with oxygen relative to the second compressible component.
 5. The method of claim 1 further comprising the step of separating a second compressible product stream comprising oxygen from the incompressible fluid product stream.
 6. The method of claim 5 wherein separating the incompressible fluid product stream from the mixed stream and separating the oxygen from the incompressible fluid product stream requires less than 1,200 Btu per pound of oxygen separated.
 7. The method of claim 5 further comprising the step of mixing the incompressible fluid product stream from which oxygen has been separated with the compressible feed stream.
 8. The method of claim 1 wherein the incompressible fluid comprises a physical solvent.
 9. The method of claim 8 wherein the physical solvent comprises a fluorinated compound.
 10. A method, comprising providing a compressible feed stream to a separation device wherein the compressible feed stream is comprised of a first compressible component and a second compressible component, wherein the first compressible component is oxygen; mixing an incompressible fluid stream comprising an incompressible fluid with the compressible feed stream in the separation device to form a mixed stream, wherein the incompressible fluid is capable of absorbing oxygen or reversibly reacting with oxygen from the compressible feed stream to form an incompressible fluid product stream; and in the separation device, separating the mixed stream into a first compressible product stream comprising at least 60% of the second compressible component and an incompressible fluid product stream comprising the first compressible component, the incompressible fluid, a chemical compound or adduct of reaction of the first compressible component with the incompressible fluid, or mixtures thereof, wherein the mixed stream has a velocity with a Mach number of greater than 0.1 in the separation device.
 11. The method of claim 10 further comprising feeding the second compressible product stream to a combustion reaction.
 12. The method of claim 10 wherein the incompressible fluid comprises a physical solvent.
 13. The method of claim 12 wherein the physical solvent comprises a fluorinated compound.
 14. The method of claim 10 further comprising: separating at least a portion of the first compressible component from the incompressible fluid product stream; and mixing the incompressible fluid product stream from which the first compressible component has been separated with the compressible feed stream.
 15. The method of claim 10 wherein a centrifugal force separator is the separating device. 